Escapement op watches



J. MUMA.

Watch.

Patented July 13, 1858.

JACOB MUMA, OF HANOVER, PENNSYLVANIA.

ESCAPEMENT OF W'ATCZ-IES.

Specification of Letters Patent No. 20,888, dated July 13, 1858.

To all whom it may concern:

Be it known that I, Jaoon MUMA, of Hanover, in the county of York and State of Pennsylvania, have invented certain new and useful Improvements in atches; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the annexed drawings, forming part of this specification, in which Figure 1, is a plan of a watch movement with my improvements. Fig. 2, is a sect-ion of the same, parallel with Fig. 1. Fig. 3, is a side view of the same showing the escapement and compensation arrangement. Figs. 4, to 8, are views illustrating the ac tion of the escapement. Fig. 9, exhibits a modification of the escapement wheel. Fig. 10, is a side view of the barrel and fusee.

Similar letters of reference indicate corresponding parts in the several figures.

To enable others skilled in the art to put my invention in practice, I will proceed to describe its construction and operation.

The escapement being the most important feature of the invention will be first de scribed. The escape wheel, A, may have. its teeth, a, (4, either of the form shown in Figs. 1 and 2, or that shown in Fig. 9, and may be made either of metal or of ruby or other jewel. If made of metal I make them of the form shown in the former figure, but if made of jewel I make them of the form shown in the latter figure. In the former case they have their two sides, 0, 0, parallel to a radial line, 6, see Fig. 2, passing through the center of the tooth, and in the latter case their sides form portions of circles, e, 6, described from equi-distant points in a circle, (Z, circumscribing the faces of the teeth. In either case their faces, 2', 2', are slightly beveled inward in the direction of their revolution which is indicated by arrows, f, Two balances, B, B, each having a hair spring, see Fig. 8, applied in the usual manner, are employed, one on each side of the escape wheel, their axis being arranged in the same plane as the axis of the escape wheel, and exactly in the circle described by the least prominent edge of the faces, 2', 2', of the escape wheel teeth, the said balances being geared together to oscillate in opposite directions, by very fine teeth which are to be cut and finished in the most accurate and smooth manner known, so as to work together with the least possible degree of friction and without lubrication. On the staff, g, of each balance is a cylinder or more properly speaking a segment of a cylinder, l1, or if, which is concentric to its respective balance, the versed sine of the said segment being about equal to onethird of the diameter of the cylinder of which it forms a portion. Each balance receives in its turn an impulse from the escape wheel by a tooth of the escape wheel working across the chord of its cylindrical segment, 72, and giving motion by the gearing to its fellow in an opposite direction, and the escape-wheel remaining for a time stationary between the operations on the segments in consequence of one of its teeth resting on the cylindrical portion or are of one or other of the segments, thus producing a perfect dead beat. The balances are intended to make about one complete revolution. The escapement wheel remains stationary during half a revolution of the balances.

The operation of the escapement is illus trated by the Figs. 2, a, 5, 6, 7 and 8; the figures from at to 8 inclusive representing the cylindrical segment of one balance and one tooth of the escape wheel. In Fig. 2, a tooth, a, of the escapement wheel is giving impulse to the segment of the right hand balance in the direction of the arrow marked near it and is just about escaping having worked nearly all across the chord of the segment, and a tooth, a, on the opposite side of the wheel is just about to fall on the arc of the segment of the left hand balance which is at the time rotating in the opposite direction to the other segment. It may be here observed that the escape wheel has an odd number of teeth so that every tooth has a space diametrically opposite to it. To return to the operation, Fig. 4t, represents the tooth, a, at the time of the escape of a, having just taken place, the said tooth a, being just arrested by falling against the arc of the segment, 72*, of the left hand balance, which continues rotating in the direction of the arrow shown near it till it has reached the position in which it is shown in Fig. 5, by which time the force of the impulse will have been counteracted by the action of the hair springs which react upon the balances and change the direction of the revolution of the segments, making the direction of the revolution of if, as shown by the arrow in Fig. 6, which represents the said segment as having gone back to the position in which it begins toreceive an impulse from the teeth, a, which now presses against the inner edge of the segment. The impulse continues as the segment turns, as 1s illustrated in Figs. 6, 7, and 8, in the latter of which figures the tooth, a, is represented about to escape and when this escape takes place, the segment, h, of the right hand balance will be in a condition to receive the tooth behind, a, which operates relatively with it in the same manner as, a, has operated relatively with, If. This alternate action on the cylindrical segments of the two balances produces an exceedingly regular escapement which is not to be influenced by any shaking or jarring of the watch, for the balances will vibrate their proper distance and neither more or less, though the watch be violently shaken in a circular direction. This escapement requires less impulse than a single balance escapement 0wing to the peculiarly effective action of the teeth of the escapement wheel on the cylinders or cylindrical segments.

The device for compensating for the variations of the balance is applied to each balance; it consists of a stout ring, C, of brass, surrounded by a closely fitting coil, D, of spring steel as shown in Fig. 3, one end, Z, of the said coil being secured to the ring, and the other end, at, being forked to receive and form a curb to the hair spring, The brass ring fits tightly to a fixed pivot, p, which is indicated by a dotted circle in Fig. 1, which is concentric to the staff of the balance, the said staff passing freely through it. The expansion and contraction of the brass ring, by changes of temperature, being greater than that of the surrounding steel coil causes the forked end of the coil to move in a circumferential direction, and thereby to increase or diminish the effective length of the hair spring and thus to diminish or increase its power, the expansion causing the effective length of the spring to be climinished and its power increased and the contraction causing its efiective length to be increased and its power diminished. The coils, D, D, may have one, two or more turns around the ring, C, as may be requisite. The regulation of the watch is effected by turning an endless screw, g, which is fitted in suitable bearings to gear with a toothed segment, 1, attached firmly to each ring, C, so as to turn both rings at once in opposite directions and with. them the coils, D, D, thus moving the forks or curbs, m, m, on the spring, to lengthen or shorten the effective length of both hair springs, as may be necessary.

The arrangements of the barrel, H, main spring, E, fusee, F, and chaln, G, 1n my watch differ from the arrangement of the corresponding parts of other watches in two particulars. In the first place, the' chain, instead of being arranged-to draw on the opposite side of the fuseev to that from whence the power is transmitted by the fusee wheel, 8, to the center pinion, t, as is illustrated by the small diagram, X, which exhibits the arrangement in other watches, is arranged to draw on the same side as that from which the power is given, as is illustrated in Fig. 1. In the old arrangement shown in diagram, X, the drag of the chain is in the direction'of the arrow, 12, and the resistance offered by the pinion is nearly in the direction of the arrow, 13, both directions being similar on opposite sides of the center of the fusee and the whole of both these forces is thrown upon the fusee pivots, thus producing the greatest possible amount of friction; but in my new arrangement which is shown best in Fig. 2, the drag of the chain which is in the direction of the arrow, 14, and the resistance offered by the pinion which is nearly in the direction of the arrow, 15, are in opposite directions on the same side of the center of the fusee and hence are made as nearly as possible to counteract each other in their efiect on the pivots of the fusee and thus the friction on the fusee pivots may be reduced to about one fifth of what it is in the old arrangement.

This new arrangement involves the arrangement of the coil of the main-spring in a direction the reverse of what it is in the old arrangement of the chain and the consequent revolution of the barrel in the reverse direction. The other point of difference in my arrangements of the barrel, main spring, chain, and fusee, consists in reversing the positions of the larger and smaller ends of the fusee, that is to say, placing the small end of the fusee next the fusee wheel, 8, instead of the large end. The effect of this is to bring the drag of the chain, at the time when the watch is fully wound up, at which time the spring is most powerful, opposite the middle of the barrel and opposite the middle of the length of the arbor, o, of the fusee, as is illustrated in Fig. 10, which eX- -hibits the chain fully wound up, instead of at one end of each, as is shown in the diagram, Y, whlch exhibits the old arrangement fully wound, thus causing the friction to be equally distributed on both ends of the barrel and both pivots, u, u, of the fusee arbor, 4), instead of nearly all on one end of the barrel and one pivot of the fusee arbor. By the above arrangements for reducing the friction on the fusee pivots and equalizing the friction in the barrel and on the fusee pivots a more easy and uniform transmission of the maintaining power is obtained and the movement of the chain will be regular instead of in a series of jumps as it is in the old arrangement, and I am enabled to jewel the barrel, which could not be done with on opposite sides of its axis when said escape wheel A and balances B B with the1r segments h if are arranged in relation to each 1 other with their axes in the same plane and the gear of said single escape wheel A with the segments h if serves the double purpose of escape and of giving impulse to the balances as specified.

J. MUMA. \Vitnesses:

73L TUSGH, JAMES L. BUCKLEY. 

